Priyanka: Good morning. My name is Priyanka, and my presentation is about light pollution.

Priyanka: About eighty percent of people in the United States now live somewhere the Milky Way cannot be seen at night. The cause is not one enormous light. It is thousands of ordinary ones, on parking lots and porches and signs, that throw their light upward instead of down.

Priyanka: The effects reach well past astronomy. Migrating birds navigate by the night sky, and a brightly lit city can pull a whole flock miles off its route. Sea turtle hatchlings crawl toward the brightest horizon, which for millions of years was the ocean.

Priyanka: Here is the encouraging part. Unlike smoke or plastic, this pollution disappears the moment the light is switched off or pointed down. A shielded fixture can fix a whole street in one night.